Device positioning

ABSTRACT

An apparatus, method and computer program is described. The method can include receiving a first measurement report from a first communication node of a mobile communication system. The first measurement report can include downlink measurement data generated at a user device in response to a positioning reference signal sent by the first communication node. The method can further include receiving a second measurement report from the first communication node. The second measurement report can include uplink measurement data generated at the first communication node in response to an uplink reference signal sent by the user device. The method can also include determining an integrity of the measurement data based on a comparison of said uplink and downlink measurement data and setting an integrity verification notification in accordance with the determined integrity.

CROSS REFERENCE TO RELATED APPLICATION

This is a Continuation of U.S. patent application Ser. No. 17/490,184filed Sep. 20, 2021, and which claims priority from Finnish PatentApplication No. 20205951, dated Sep. 30, 2020. The contents of theseapplications are hereby incorporated by reference.

FIELD

This present specification relates to device positioning. In particular,the present specification relates to integrity in device positioning.

BACKGROUND

Although arrangements for estimating the position of a device, such as auser device, based on signals transmitted within a mobile communicationsystem are known, there remains room for further developments in thisfield.

SUMMARY

In a first aspect, this specification describes an apparatus (such as alocation management function) comprising means for performing: receivinga first measurement report from a first communication node of a mobilecommunication system, wherein the first measurement report includesdownlink measurement data generated at a user device in response to apositioning reference signal sent by the first communication node;receiving a second measurement report from the first communication node,wherein the second measurement report includes uplink measurement datagenerated at the first communication node in response to an uplinkreference signal (e.g. a sounding reference signal) sent by the userdevice; determining an integrity of the measurement data based on acomparison of said uplink and downlink measurement data; and setting anintegrity verification notification in accordance with the determinedintegrity. The first communication node may be a serving base station ofthe user device.

The downlink measurement data may include downlink time delay or time ofarrival data and the uplink measurement data includes uplink time delayor time of arrival data. Further, the means for performing determiningthe integrity of the measurement data may determine whether the uplinkand downlink time delay or time of arrival data are consistent. Themeans for performing determining whether the downlink time delay or timeof arrival and the uplink time delay or time of arrival data areconsistent may comprise means for performing determining whether adifference between the downlink time delay or time of arrival and theuplink time delay or time of arrival is below a first threshold.

The uplink and downlink measurement data may include angle of arrivaland angle of departure data. Furthermore, the means for performingdetermining the integrity of the measurement data may determine whetherthe angle of arrival and angle of departure data are consistent.

Some example embodiments further comprise receiving a third measurementreport from a second communication node of the mobile communicationsystem, wherein the third measurement report includes uplink measurementdata generated at the second communication node in response to theuplink reference signal sent by the user device, wherein the firstmeasurement report includes downlink measurement data generated at theuser device in response to a positioning reference signal sent by thesecond communication node. The second communication node may be aneighbour base station of the user device.

Some example embodiment further comprise: determining (e.g. based onangle of arrival and/or angle of departure data) a first angle betweenthe user device, the first communication node and the secondcommunication node; determining (e.g. based on angle of arrival and/orangle of departure data) a second angle between the user device, thesecond communication node and the first communication node; determining(e.g. based on time delay data) a first distance between the firstcommunication node and the user device; and determining (e.g. based ontime delay data) a second distance between the second communication nodeand the user device, wherein the means for performing determining theintegrity of the measurement data determines whether the first andsecond angles and the first and second distances are consistent. Themeans for performing determining the integrity of the measurement datamay determine whether a difference between a ratio of the sine of thefirst angle and the second distance and a ratio of the sine of thesecond angle and the first distance is below a second threshold.

Some example embodiments further comprise: determining (e.g. based onangle of arrival and/or angle of departure data) a/the first anglebetween the user device, the first communication node and the secondcommunication node; determining (e.g. based on angle of arrival and/orangle of departure data) a/the second angle between the user device, thesecond communication node and the first communication node; anddetermining a third angle between the first communication node, the userdevice and the second communication node, wherein the means forperforming determining the integrity of the measurement data determinessaid integrity based on a sum of the first, second and third angles(e.g. by determining whether that sum, minus 180 degrees, is below athird threshold).

In some example embodiments, setting the integrity verificationnotification comprises setting an integrity verification notificationsignal (e.g. a flag).

Some example embodiments further comprise sending configurationinstructions to the first communication node (and optionally to thesecond communication node) requesting said first and second measurementreports (and optionally the third measurement report).

Some example embodiments further comprise estimating a position of theuser device based on an angles of arrival of transmissions from the userdevice at the first communication node and another communication nodeand the distance between the first communication node and said anothercommunication node (e.g. the second communication node referred toabove). The position estimate may be determined in the event that theintegrity verification notification is set (e.g. data from the userdevice is deemed to be untrustworthy).

In a second aspect, this specification describes an apparatus (such as acommunication node or a mobile communication system) comprising meansfor performing: transmitting a positioning reference signal; receiving adownlink measurement report from a user device, wherein the downlinkmeasurement report include downlink measurement data generated at a userdevice in response to the positioning reference signal; sending a firstmeasurement report to a server (e.g. a location management function),wherein the first measurement report includes said downlink measurementreport; receiving an uplink reference signal transmission (e.g. asounding reference signal) from the user device; generating an uplinkmeasurement report including uplink measurement data generated inresponse to the received uplink reference signal; and sending ameasurement report to a server, wherein the second measurement reportincludes said uplink measurement report.

In the first or the second aspect, the said means may comprise: at leastone processor; and at least one memory including computer program code,the at least one memory and the computer program configured, with the atleast one processor, to cause the performance of the apparatus.

In a third aspect, this specification describes a method comprising:receiving a first measurement report from a first communication node ofa mobile communication system, wherein the first measurement reportincludes downlink measurement data generated at a user device inresponse to a positioning reference signal sent by the firstcommunication node; receiving a second measurement report from the firstcommunication node, wherein the second measurement report includesuplink measurement data generated at the first communication node inresponse to an uplink reference signal sent by the user device;determining an integrity of the measurement data based on a comparisonof said uplink and downlink measurement data; and setting an integrityverification notification in accordance with the determined integrity.

The downlink measurement data may include downlink time delay or time ofarrival data and the uplink measurement data includes uplink time delayor time of arrival data. Further, determining the integrity of themeasurement data may comprise determining whether the uplink anddownlink time delay or time of arrival data are consistent. Moreover,determining whether the downlink time delay or time of arrival and theuplink time delay or time of arrival data are consistent may comprisedetermining whether a difference between the downlink time delay or timeof arrival and the uplink time delay or time of arrival is below a firstthreshold.

Determining the integrity of the measurement data may comprisingdetermining whether an angle of arrival and an angle of departure dataare consistent.

Some example embodiments further comprise receiving a third measurementreport from a second communication node of the mobile communicationsystem, wherein the third measurement report includes uplink measurementdata generated at the second communication node in response to theuplink reference signal sent by the user device, wherein the firstmeasurement report includes downlink measurement data generated at theuser device in response to a positioning reference signal sent by thesecond communication node. The second communication node may be aneighbour base station of the user device.

Some example embodiment further comprise: determining (e.g. based onangle of arrival and/or angle of departure data) a first angle betweenthe user device, the first communication node and the secondcommunication node; determining (e.g. based on angle of arrival and/orangle of departure data) a second angle between the user device, thesecond communication node and the first communication node; determining(e.g. based on time delay data) a first distance between the firstcommunication node and the user device; and determining (e.g. based ontime delay data) a second distance between the second communication nodeand the user device, wherein the means for performing determining theintegrity of the measurement data determines whether the first andsecond angles and the first and second distances are consistent.Determining the integrity of the measurement data may comprisedetermining whether a difference between a ratio of the sine of thefirst angle and the second distance and a ratio of the sine of thesecond angle and the first distance is below a second threshold.

Some example embodiments further comprise: determining (e.g. based onangle of arrival and/or angle of departure data) a/the first anglebetween the user device, the first communication node and the secondcommunication node; determining (e.g. based on angle of arrival and/orangle of departure data) a/the second angle between the user device, thesecond communication node and the first communication node; anddetermining a third angle between the first communication node, the userdevice and the second communication node, wherein the means forperforming determining the integrity of the measurement data determinessaid integrity based on a sum of the first, second and third angles(e.g. by determining whether that sum, minus 180 degrees, is below athird threshold).

In some example embodiments, setting the integrity verificationnotification comprises setting an integrity verification notificationsignal (e.g. a flag).

Some example embodiments further comprise sending configurationinstructions to the first communication node (and optionally to thesecond communication node) requesting said first and second measurementreports (and optionally the third measurement report).

Some example embodiments further comprise estimating a position of theuser device based on an angles of arrival of transmissions from the userdevice at the first communication node and another communication nodeand the distance between the first communication node and said anothercommunication node (e.g. the second communication node referred toabove). The position estimate may be determined in the event that theintegrity verification notification is set (e.g. data from the userdevice is deemed to be untrustworthy).

In a fourth aspect, this specification describes a method comprising:transmitting a positioning reference signal; receiving a downlinkmeasurement report from a user device, wherein the downlink measurementreport include downlink measurement data generated at a user device inresponse to the positioning reference signal; sending a firstmeasurement report to a server (e.g. a location management function),wherein the first measurement report includes said downlink measurementreport; receiving an uplink reference signal transmission (e.g. asounding reference signal) from the user device; generating an uplinkmeasurement report including uplink measurement data generated inresponse to the received uplink reference signal; and sending ameasurement report to a server, wherein the second measurement reportincludes said uplink measurement report.

In a fifth aspect, this specification describes computer-readableinstructions which, when executed by computing apparatus, cause thecomputing apparatus to perform (at least) any method as described withreference to the third or fourth aspects.

In a sixth aspect, this specification describes a computer-readablemedium (such as a non-transitory computer-readable medium) comprisingprogram instructions stored thereon for performing (at least) any methodas described with reference to the third or fourth aspects.

In a seventh aspect, this specification describes an apparatuscomprising: at least one processor; and at least one memory includingcomputer program code which, when executed by the at least oneprocessor, causes the apparatus to perform (at least) any method asdescribed with reference to the third or fourth aspects.

In an eighth aspect, this specification describes a computer programcomprising instructions for causing an apparatus to perform at least thefollowing: receiving a first measurement report from a firstcommunication node of a mobile communication system, wherein the firstmeasurement report includes downlink measurement data generated at auser device in response to a positioning reference signal sent by thefirst communication node; receiving a second measurement report from thefirst communication node, wherein the second measurement report includesuplink measurement data generated at the first communication node inresponse to an uplink reference signal sent by the user device;determining an integrity of the measurement data based on a comparisonof said uplink and downlink measurement data; and setting an integrityverification notification in accordance with the determined integrity.

In a ninth aspect, this specification describes a computer programcomprising instructions for causing an apparatus to perform at least thefollowing: transmitting a positioning reference signal; receiving adownlink measurement report from a user device, wherein the downlinkmeasurement report include downlink measurement data generated at a userdevice in response to the positioning reference signal; sending a firstmeasurement report to a server (e.g. a location management function),wherein the first measurement report includes said downlink measurementreport; receiving an uplink reference signal transmission (e.g. asounding reference signal) from the user device; generating an uplinkmeasurement report including uplink measurement data generated inresponse to the received uplink reference signal; and sending ameasurement report to a server, wherein the second measurement reportincludes said uplink measurement report.

In a tenth aspect, this specification describes an apparatus comprisingmeans (such as location management function) for receiving a firstmeasurement report from a first communication node of a mobilecommunication system, wherein the first measurement report includesdownlink measurement data generated at a user device in response to apositioning reference signal sent by the first communication node; means(such as the location management function) for receiving a secondmeasurement report from the first communication node, wherein the secondmeasurement report includes uplink measurement data generated at thefirst communication node in response to an uplink reference signal sentby the user device; means (such as control module or processor) fordetermining an integrity of the measurement data based on a comparisonof said uplink and downlink measurement data; and means (such as anoutput of the location management function) for setting an integrityverification notification in accordance with the determined integrity.

In an eleventh aspect, this specification describes an apparatuscomprising means such as a communication node of a mobile communicationsystem) for transmitting a positioning reference signal; means (such asthe communication node) for receiving a downlink measurement report froma user device, wherein the downlink measurement report include downlinkmeasurement data generated at a user device in response to thepositioning reference signal; means (such as an output of thecommunication node) for sending a first measurement report to a server,wherein the first measurement report includes said downlink measurementreport; means (such as the communication node) for receiving an uplinkreference signal transmission from the user device; means (such as acontrol module or processor) for generating an uplink measurement reportincluding uplink measurement data generated in response to the receiveduplink reference signal; and means (such as the output of thecommunication node) for sending a measurement report to a server,wherein the second measurement report includes said uplink measurementreport.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments will now be described, by way of example only, withreference to the following schematic drawings, in which:

FIGS. 1 and 2 are block diagrams of systems in accordance with exampleembodiments;

FIG. 3 is a flow chart showing an algorithm in accordance with anexample embodiment;

FIGS. 4 and 5 are block diagrams of systems in accordance with exampleembodiments;

FIGS. 6 and 7 are message flow sequences in accordance with exampleembodiments;

FIG. 8 is a flow chart showing an algorithm in accordance with anexample embodiment;

FIG. 9 is a block diagram of a system in accordance with an exampleembodiment;

FIG. 10 is a flow chart showing an algorithm in accordance with anexample embodiment;

FIG. 11 is a block diagram of a system in accordance with an exampleembodiment;

FIGS. 12 and 13 are flow charts showing algorithms in accordance withexample embodiments; and

FIG. 14 is a block diagram of a system in accordance with an exampleembodiment;

FIG. 15 is a block diagram of components of a system in accordance withan example embodiment; and

FIGS. 16A and 16B show tangible media, respectively a removablenon-volatile memory unit and a compact disc (CD) storingcomputer-readable code which when run by a computer perform operationsaccording to example embodiment.

DETAILED DESCRIPTION

The scope of protection sought for various embodiments of the inventionis set out by the independent claims. The embodiments and features, ifany, described in the specification that do not fall under the scope ofthe independent claims are to be interpreted as examples useful forunderstanding various embodiments of the invention.

In the description and drawings, like reference numerals refer to likeelements throughout.

In 3GPP Rel-16 and Rel-17 NR positioning studies, mobile networks (MNs)may require locating the position of a user equipment (UE) to providespecific services or applications (location-basedservices/applications). To determine the position of a UE, 3GPP definesmultiple methods. For example, a mobile network may estimate UEpositioning using network-based methods requiring cooperation by the UE(UE-assisted positioning), or a position estimation may be performed bythe UE (UE-based positioning).

A Location Management Function (LMF) may be used to coordinatepositioning in the 5G NR system. According to the 3GPP description ofnew radio (NR) positioning enhancement, integrity (relating to thereliability and security of a positioning measurement) is a metric forpositioning techniques that will be introduced in Rel-17 and beyond.

FIG. 1 is a block diagram of system, indicated generally by thereference numeral 10, in accordance with an example embodiment. Thesystem 10 comprises a base station 12 and a plurality of user devices incommunication with the base station. Positioning estimates regarding theuser devices may be determined. In the system 10, the user device 14 isa malicious user device that may seek to provide false information aboutits position.

Positioning integrity includes mobile network managements on positioningmeasurement accuracy and also managements against malicious attacksdisturbing positioning measurements or positioning-related service. Forexample, integrity diagnosis may be used by a user device or apositioning server to determine whether positioning information isreliable or not. If the integrity check declares measurements to beunreliable, such measurements should not be used by the application orthe user. Also, a malicious UE (such as the user device 14 in the system10) having hacking intentions may attempt to transmit jamming signals orgenerate fake measurements. Such issues may be relevant to security,since there are application programmes using the positioning informationas a security key. Therefore, integrity diagnosis may be important formany applications to provide positioning in secured channels.

As positioning-based application services are introduced in 4G/5Gsystems, positioning information is generally becoming more important.In order to support such services, accurate positioning measurementswith high integrity and security may be required.

FIG. 2 is a block diagram of system, indicated generally by thereference numeral 20, in accordance with an example embodiment. Thesystem 20 comprises a base station 22 (such as the base station 12described above), a location management function (LMF) 24 and a userdevice (UE) 26. The base station 12 is in two-way communication withboth the LMF 24 and the user device 26. The LMF 24 includes policies forchecking accuracy and integrity of measurement data relating the userdevice 26.

Integrity determination can be important for many reasons. First, widedistribution of measurement error in a radio side can cause localizationinaccuracy. Such measurements error may happen in various ways. It canbe due to multiple path channel propagations or noisy channels, orintentional and unintentional interferences include positioning jammingand interfering signals, resulting in measurement errors. Second,although it may not know a source of the measurement error, when thepositioning service is used for security applications, predictioncapabilities of screening out inaccurate measurements or detection ofthe presence of malicious UEs may be required. This may be theresponsibility of all network nodes (such as the base station 22, theLMF 24). Third, if a network senses suspicious measurements orbehaviours, a malicious UE may seek to impersonate true UE positioning,and may generate erroneous measurements with malicious intention. Thisthreat is valid for the location methods relying on a training database.Such a training database is typically populated with data collected bythe 5G network and relevant parts of it are then transferred to a mobiledevice for the positioning purpose. Errors, for example due to data frommalicious user devices, can reduce the accuracy of the transmitteddatabase, and thus the accuracy and robustness of the location.

FIG. 3 is a flow chart showing an algorithm, indicated generally by thereference numeral 30, in accordance with an example embodiment.

The algorithm 30 starts at operation 32 where a first measurementsreport is received at a server (such as the LMF 24) from a firstcommunication node (such as the base station 22) of a mobilecommunication system. The first measurement report may include downlinkmeasurement data generated at a user device (such as the user device 26)in response to a positioning reference signal sent by the firstcommunication node.

At operation 34, a second measurement report is received at the serverfrom the first communication node. The second measurement report mayinclude uplink measurement data generated at the first communicationnode in response to an uplink reference signal (e.g. a soundingreference signal) sent by the user device.

At operation 36, an integrity of the measurement data is determinedbased on a comparison of said uplink and downlink measurement data.

Finally, at operation 38, an integrity verification notification (suchas a flag) is set by the server, in accordance the integrity determinedin the operation 36.

FIG. 4 is a block diagram of system, indicated generally by thereference numeral 40, in accordance with an example embodiment. Thesystem 40 may be used to implement the algorithm 30 described above.

The system 40 comprises a first communication node 42 (such as the basestation 22 described above) and a first user device 44 (such as the userdevice 26 described above).

The user device 44 generates downlink measurement data in response to apositioning reference signal (PRS) sent by the first communication node42. The downlink measurement data may be provided as the firstmeasurement report of the operation 32 described above. Similarly, thecommunication node 42 generates uplink measurement data in response to asounding reference signal (SRS) sent by the user device 44. The uplinkmeasurement data may be provided as the second measurement report of theoperation 34 described above.

The downlink measurement data may include downlink time delay or time ofarrival data that is a measure of the time delay between a signal beingtransmitted by the communication node 42 and being received at the userdevice 44. Similarly, the uplink measurement data may include uplinktime delay or time of arrival data that is a measure of the time delaybetween a signal being transmitted by the user device and being receivedat the communication node. The operation 36 of the algorithm 30 maydetermine integrity by determining whether the uplink and downlink timedelay or time of arrival data are consistent.

By way of example, in an observed time difference of arrival algorithm(OTDoA), a reference signal time difference (RSTD) may be measured bythe user device 44, while uplink time difference of arrival (UTDoA) mayinclude the reporting of absolute time stamps at a gNB receiver (such asthe first communication node 42). An LMF may then calculate a referencesignal time difference (RSTD) using the UL time stamps as timedifference between serving cell and a neighboring gNB (i.e.Δt_(UL)=t_(gNB)−t_(serving)).

In such as arrangement, the operation 38 may set the verificationnotification based on the following formula:

verification flag=boolean(|Δt _(DL) −Δt _(UL)|<ε  (1)

where ε is a threshold of acceptance.

FIG. 5 is a block diagram of a system, indicated generally by thereference numeral 50, in accordance with an example embodiment. Thesystem 50 comprises the first communication node 42 and the first userdevice 44 of the system 40 described above and further comprises asecond communication node 52. Both the first and second communicationnodes 42 and 52 are in two-way communication with the user device 44,thereby enabling further time difference data to be obtained.

The system 50 enables more positioning data to be obtained (andcompared) and may therefore be more accurate than the system 40.Clearly, more than two communication nodes could be provided.

FIG. 6 is a message flow sequence, indicated generally by the referencenumeral 60, in accordance with an example embodiment. The message flowsequence 60 is an example implementation of the algorithm 30 describedabove and may be implemented using the system 50.

The message flow sequence 60 shows messages transmitted between a firstuser device UE (such as the first user device 44), a first (serving)base station BS1 (such as the first communication node 42), a secondbase station BS2 (such as the second communication node 52) and alocation management function LMF. The second base station BS2 may be aneighbour base station.

The message flow sequence 60 starts with the LMF sending configurationinstructions 61 to the first communication node BS1 (and optionally tothe second communication node BS2) requesting measurement reports, suchas the measurement reports discussed above with reference to thealgorithm 30.

In response to the message 61, the serving base station BS1 sends apositioning reference signal (PRS) to user devices served by the BS1,including the first user device UE.

On receipt of the PRS signal, the first user device UE determines adownlink (DL) measurement (such downlink time delay or time of arrivaldata) and provides that DL measurement to the serving base station in amessage 63 a. That downlink data is provided by the serving base stationto the LMF in a message 63 b. The receipt of the message 63 b at the LMFis an example of the operation 32 of the algorithm 30 described above.

The LMF also sends an SRS transmission request message 64 a to theserving base station BS1, which transmission request is sent by theserving base station to the first user device UE in a message 64 b. Inresponse, the UE provides a sounding reference signal (SRS) transmissionthat is received at the serving base station BS1 (message 65 a) and isalso received at the second base station BS2 (message 65 b).

Both the serving base station BS1 and the second base station BS2generate uplink measurements (e.g. uplink time difference of arrivalmeasurements) based on the received SRS transmissions from both thefirst user device and the second user device. First uplink measurementsare sent by the serving base station to the LMF in message 66 a andsecond uplink measurement are sent by the second base station BS2 to theLMF in message 66 b. The receipt of the message 66 a at the LMF is anexample of the operation 34 of the algorithm 30 described above.

The location management function LMF determines an integrity of themeasurement data for each user device based on a comparison of saiduplink and downlink measurement data received in the messages 63 b, 66 aand 66 b. An integrity verification notification (such as a flag) may beset by the LMF based on the determined integrity and may be provided tothe serving base station BS1 as an integrity verification notificationsignal 67.

FIG. 7 is a message flow sequence, indicated generally by the referencenumeral 70, in accordance with an example embodiment. The message flowsequence 70 shows messages transmitted between the first (serving) userdevice UE, the first (serving) base station BS1, the second base stationBS2 and the location management function LMF of the message flowsequence 60 and a second user device. The second user device is amalicious user device.

The message flow sequence 70 starts with the LMF sending theconfiguration instructions 61 to the first communication node BS1 (andoptionally to the second communication node BS2) requesting measurementreports, such as the measurement reports discussed above with referenceto the algorithm 30.

In response to the message 61, the serving base station BS1 sends apositioning reference signal (PRS) to user devices served by the BS1,including the first user device and the second user device.

On receipt of the PRS signals, the first user device determines adownlink (DL) measurement are provides that DL measurement to theserving base station in the message 63 a discussed above. Similarly, thesecond user device provides DL measurement data to the serving basestation in a message 73 a. The downlink measurement data provided by thesecond user device in the message 73 a may be faked or falsified in someway.

That downlink data received by the serving base station in the messages63 a and 73 a are provided to the LMF in a message 73 b. The receipt ofthe message 73 b at the LMF is an example of the operation 32 of thealgorithm 30 described above.

The LMF also sends the SRS transmission request message 64 a to theserving base station BS1, which transmission request is sent by theserving base station to the first user device in the message 64 b and tothe second user device in a message 74.

In response to the SRS transmission request, the first UE provides asounding reference signal (SRS) transmission that is received at theserving base station BS1 (message 65 a) and is also received at thesecond base station BS2 (message 65 b). Similarly, the second userdevice provides an SRS transmission that is received at the serving basestation (message 75 a) and is also received at the second base stationBS2 (message 75 b)

Both the serving base station BS1 and the second base station BS2generate uplink measurements (e.g. uplink time difference of arrivalmeasurements) based on the received SRS transmission. First uplinkmeasurements are sent by the serving base station to the LMF in message76 a and second uplink measurement are sent by the second base stationBS2 to the LMF in message 76 b. The receipt of the message 66 a at theLMF is an example of the operation 34 of the algorithm 30 describedabove.

The location management function LMF determines an integrity of themeasurement data based on a comparison of said uplink and downlinkmeasurement data for both user devices received in the messages 73 b, 76a and 76 b. An integrity verification notification (such as a flag) maybe set for each user device by the LMF based on the determine integrityand may be provided as to the serving base station BS1 as an integrityverification notification signal 67.

The algorithm 30, as described above with reference to FIG. 3 , may beimplemented at the location management function of the message flowsequences 60 and 70 described above. FIG. 8 is a flow chart showing analgorithm, indicated generally by the reference numeral 80, inaccordance with an example embodiment. The algorithm 80 may beimplemented at a communication node, such as the serving base stationBS1 of the message flow sequences 60 and 70.

The algorithm 80 starts at operation 81, where a positioning referencesignal (PRS) is transmitted by a communication node.

At operation 82, one or more downlink measurement report(s) are receivedat the communication node from one or more user devices. The downlinkmeasurement report(s) include downlink measurement data generated at auser device in response to the positioning reference signal transmittedin the operation 81. The downlink measurement data may be based on timedelay data, but other data may be used, such as angle data, as discussedfurther below.

At operation 83, a first measurement report is sent to a server (e.g. alocation management server). The first measurement report includes thedownlink measurement report(s) received in the operation 82.

At operation 84, an uplink reference signal transmission (e.g. asounding reference signal) is received from the user device(s). Inresponse to the receive uplink reference signal(s), an uplinkmeasurement report is generated at operation 85. The uplink measurementreport includes uplink measurement data generated in response to thereceived uplink reference signal(s).

Finally, at operation 86, a measurement report is sent to the server(e.g. the LMF), wherein the second measurement report includes theuplink measurement report generated in the operation 85.

The user of uplink and downlink timing data is not the only mechanism bywhich positioning and position integrity can be verified. For example,angle or arrival (AoA) and/or angle of departure (AoD) data may be usedin the algorithms 30 and 80, as discussed in detail below.

FIG. 9 is a block diagram of system, indicated generally by thereference numeral 90, in accordance with an example embodiment.

The system 90 comprises a first communication node 91 and a secondcommunication node 92 (similar to the first and second communicationnodes 42 and 52 described above). The system 90 further comprises afirst user device 93 (similar to the first user device 44 describedabove) and may comprise malicious (or fake) user device 94. Both thefirst and second communication nodes 91 and 92 are in two-waycommunication with the first user device 93 (and may be in two-waycommunication with the malicious user device 94).

As shown in FIG. 9 , transmissions from the first user device 93 arriveat the first communication node 91 at a first angle Ø1, and arrive atthe second communication node 92 at a second angle Ø2. Those angles arethe angles of arrival (AoA) of the respective transmissions.

As also shown in FIG. 9 , the distance between the first communicationnode 91 and the first user device 93 is given by d1 and the distancebetween the second communication node 92 and the first user device 93 isgiven by d2.

A location management function (such as the LMF 24 of the system 20) caninvestigate the angle and distance data relating to a user device usingtriangle rules, as discussed further below.

FIG. 10 is a flow chart showing an algorithm, indicated generally by thereference numeral 100, in accordance with an example embodiment. Thealgorithm 100 may be implemented using the system 90 described above.

The algorithm 100 starts at operation 102, where the first angle Ø1between the user device, the first communication node and the secondcommunication node is determined and the second angle Ø2 between theuser device, the second communication node and the first communicationnode is determined. The first and second angles may be based on angle ofarrival and/or angle of departure data.

At operation 104, a first distance (d1) between the first communicationnode and the user device is determined and a second distance (d2)between the second communication node and the user device is determined.The first and second distances may be determined based on time delaydata, as discussed further below.

At operation 106, an integrity of the measurement data determined in theoperations 102 and 104 may be determined based on whether the first andsecond angles and the first and second distances are consistent.

Whether the angles and the distances are consistent may be based onwhether a difference between a ratio of the sine of the first angle andthe second distance and a ratio of the sine of the second angle and thefirst distance is below a second threshold, for example in accordancewith the following equation:

$\begin{matrix}{{{verification}{flag}} = {{boolean}\left( {{❘{\frac{\sin\varnothing_{1}}{\Delta t2} - \frac{\sin\varnothing_{2}}{\Delta t1}}❘} < \varepsilon} \right)}} & (2)\end{matrix}$

where Δt1, Δt2 are absolute travel times between a communication nodeand the relevant user device and are therefore indicative of thedistances d1 and d2 described above. In some example embodiments, thetime of arrival measurements may be made in terms of time difference orRX time stamps and the absolute travel time are separately calculated.If DL/UL transmission are available for time measurements, round-triptime (RTT) measurement gives absolute travel time. Alternatively, iftiming advance values are available, the network can know TX time stampat UE side (i.e. Δt=(RX time stamp−TX time stamp)).

A location management function (LMF) can directly apply the measurementsoutlined above as part of a checking algorithm. As described above, amalicious used device might seek to fake or conceal its locations. Ifso, it may be difficult for the malicious used device to provide data tothe communication nodes that will result in the equation (2) above beingsatisfied.

It should be noted that the test in (2) set out above is applicable aslong as the malicious user device 94 transmits a signal. It does notrequire any measurements from the malicious user device 94 side that maywant to hide itself.

The principles described above with reference to the system 90 may beused in the algorithm 30 described above. The uplink and downlinkmeasurement data received in the operation 32 may include angle ofarrival and angle of departure data. The integrity of the measurementdata may be determined in the operation 36 based (at least in part) onwhether the angle of arrival and angle of departure data are consistent,as discussed above.

FIG. 11 is a block diagram of a system, indicated generally by thereference numeral 110, in accordance with an example embodiment.

The system 110 comprises the first communication node 91, the secondcommunication node 92 and the first user device 93 described above andmay comprise the malicious (or fake) user device 94 described above.Both the first and second communication nodes 91 and 92 are in two-waycommunication with the first user device 93 (and may be in two-waycommunication with the malicious user device 94).

As shown in FIG. 11 , transmissions from the first user device 93 arriveat the first communication node 91 at a first angle Ø1, and arrive atthe second communication node 92 at a second angle Ø2. Those angles arethe angles of arrival (AoA) of the respective transmissions at thecommunication nodes. Further, an angle between the first communicationnode, the first user device and the second communication node islabelled as Ø_(UE). The angle Ø_(UE) may be determined based on angle ofarrival and/or angle of departure data at the first user device 93.

The distance between the first communication node 91 and the first userdevice 93 is expressed as Δt1 and the distance between the secondcommunication node 92 and the first user device 93 is expressed as Δt2.

FIG. 12 is a flow chart showing an algorithm, indicated generally by thereference numeral 120, in accordance with an example embodiment. Thealgorithm 120 may be implemented using the system 110 described above.

The algorithm 120 starts at operation 122, where a first angle Ø1between the user device, the first communication node and the secondcommunication node is determined and a second angle Ø2 between the userdevice, the second communication node and the first communication nodeis determined. The first and second angles may be based on angle ofarrival and/or angle of departure data.

At operation 104, a third angle Ø_(UE) between the first communicationnode, the user device and the second communicate node is determined. Thethird angle may be determined based on angle of arrival and/or angle ofdeparture data at the respective user device.

At operation 106, an integrity of the measurement data determined in theoperations 102 and 104 may be determined based on whether the first,second and third angles sum up to 180 degrees to within a definedtolerance or threshold. This may be expressed as follows:

verification flag=boolean(|Ø1+Ø2+Ø_(UE)−180|<ε)   (3)

As described above, a malicious used device might seek to fake orconceal its locations. If so, it may be difficult for the malicious useddevice to provide data to the communication nodes that will result inthe equation (3) above being satisfied.

In the event that an integrity determination identifies a maliciousdevice, an attempt may be made to determine a true location of thatdevice. In this way, a malicious (or suspected malicious) device may betracked.

FIG. 13 is a flow chart showing an algorithm, indicated generally by thereference numeral 130, in accordance with an example embodiment.

The algorithm 130 starts at operation 132, where a malicious device isidentified. For example, one or more of the algorithms described abovemay be used to identify a malicious device.

At operation 134, a position estimate for the device identified at theoperation 132 is determined. As described further below, the positionestimate obtained in the operation 134 may be based on data that isdifficult to fake or spoof (such as angle of arrival data for signalsreceived at a communication node from the malicious (or a suspectedmalicious) device).

FIG. 14 is a block diagram, indicated generally by the reference numeral140, of a system in accordance with an example embodiment.

The system 140 comprises a first communication node 141 and a secondcommunication node 142 (similar to the first and second communicationnodes 91 and 92 described above). The system 140 further comprises afirst user device 143 (similar to the first user device 93 describedabove) and may comprise a malicious user device 144 (similar to thedevice 94 described above). Both the first and second communicationnodes 141 and 142 are in two-way communication with the first userdevice 143 and the malicious user device 144.

Let Ø1 _(f), denote the angle of arrival (AoA) of communications fromthe malicious user device 144 at the first communication node 141, Ø2_(f) denote the angle of arrive of communications from the malicioususer device 144 at the second communication node 142, and d_(BS) denotethe distance between the first and second communication nodes. Using thetriangle rules in (1), (2), we can estimate the corresponding distancesbetween the user device 144 and the respective communication nodes as:

$\begin{matrix}{{= \frac{{\sin({\varnothing 1})} \times d_{BS}}{\sin\left( {180 - {{\varnothing 1}f} - {{\varnothing 2}f}} \right)}}{= \frac{{\sin({\varnothing 2})} \times d_{Bs}}{\sin\left( {180 - {{\varnothing 1}f} - {{\varnothing 2}f}} \right)}}} & (4)\end{matrix}$

Where (as shown in FIG. 14 ):

-   -   is the distance between the malicious user device 144 and the        first communication node 141; and    -   is the distance between the malicious user device 144 and the        second communication node 142.

In this way, an estimate of the position of the malicious (or suspectedmalicious) user device 144 can be determined based only on angle ofarrival data determined at the first and second communication nodes(which data are difficult to fake or spoof) and the distance between thefirst and second communication nodes (which distance is typically knowprecisely).

For completeness, FIG. 15 is a schematic diagram of components of one ormore of the example embodiments described previously, which hereafterare referred to generically as a processing system 300. The processingsystem 300 may, for example, be the apparatus referred to in the claimsbelow.

The processing system 300 may have a processor 302, a memory 304 closelycoupled to the processor and comprised of a RAM 314 and a ROM 312, and,optionally, a user input 310 and a display 318. The processing system300 may comprise one or more network/apparatus interfaces 308 forconnection to a network/apparatus, e.g. a modem which may be wired orwireless. The network/apparatus interface 308 may also operate as aconnection to other apparatus such as device/apparatus which is notnetwork side apparatus. Thus, direct connection betweendevices/apparatus without network participation is possible.

The processor 302 is connected to each of the other components in orderto control operation thereof.

The memory 304 may comprise a non-volatile memory, such as a hard diskdrive (HDD) or a solid state drive (SSD). The ROM 312 of the memory 304stores, amongst other things, an operating system 315 and may storesoftware applications 316. The RAM 314 of the memory 304 is used by theprocessor 302 for the temporary storage of data. The operating system315 may contain code which, when executed by the processor implementsaspects of the algorithms and message flow sequences 30, 60, 70, 80,100, 120 and 130 described above. Note that in the case of smalldevice/apparatus the memory can be most suitable for small size usagei.e. not always a hard disk drive (HDD) or a solid state drive (SSD) isused.

The processor 302 may take any suitable form. For instance, it may be amicrocontroller, a plurality of microcontrollers, a processor, or aplurality of processors.

The processing system 300 may be a standalone computer, a server, aconsole, or a network thereof. The processing system 300 and neededstructural parts may be all inside device/apparatus such as IoTdevice/apparatus i.e. embedded to very small size.

In some example embodiments, the processing system 300 may also beassociated with external software applications. These may beapplications stored on a remote server device/apparatus and may runpartly or exclusively on the remote server device/apparatus. Theseapplications may be termed cloud-hosted applications. The processingsystem 300 may be in communication with the remote serverdevice/apparatus in order to utilize the software application storedthere.

FIGS. 16A and 16B show tangible media, respectively a removable memoryunit 365 and a compact disc (CD) 368, storing computer-readable codewhich when run by a computer may perform methods according to exampleembodiments described above. The removable memory unit 365 may be amemory stick, e.g. a USB memory stick, having internal memory 366storing the computer-readable code. The internal memory 366 may beaccessed by a computer system via a connector 367. The CD 368 may be aCD-ROM or a DVD or similar. Other forms of tangible storage media may beused. Tangible media can be any device/apparatus capable of storingdata/information which data/information can be exchanged betweendevices/apparatus/network.

Embodiments of the present invention may be implemented in software,hardware, application logic or a combination of software, hardware andapplication logic. The software, application logic and/or hardware mayreside on memory, or any computer media. In an example embodiment, theapplication logic, software or an instruction set is maintained on anyone of various conventional computer-readable media. In the context ofthis document, a “memory” or “computer-readable medium” may be anynon-transitory media or means that can contain, store, communicate,propagate or transport the instructions for use by or in connection withan instruction execution system, apparatus, or device, such as acomputer.

Reference to, where relevant, “computer-readable medium”, “computerprogram product”, “tangibly embodied computer program” etc., or a“processor” or “processing circuitry” etc. should be understood toencompass not only computers having differing architectures such assingle/multi-processor architectures and sequencers/parallelarchitectures, but also specialised circuits such as field programmablegate arrays FPGA, application specify circuits ASIC, signal processingdevices/apparatus and other devices/apparatus. References to computerprogram, instructions, code etc. should be understood to expresssoftware for a programmable processor firmware such as the programmablecontent of a hardware device/apparatus as instructions for a processoror configured or configuration settings for a fixed functiondevice/apparatus, gate array, programmable logic device/apparatus, etc.

If desired, the different functions discussed herein may be performed ina different order and/or concurrently with each other. Furthermore, ifdesired, one or more of the above-described functions may be optional ormay be combined. Similarly, it will also be appreciated that the flowdiagrams and message flow sequences of FIGS. 3, 6, 7, 8, 10, 12 and 13are examples only and that various operations depicted therein may beomitted, reordered and/or combined.

It will be appreciated that the above described example embodiments arepurely illustrative and are not limiting on the scope of the invention.Other variations and modifications will be apparent to persons skilledin the art upon reading the present specification.

Moreover, the disclosure of the present application should be understoodto include any novel features or any novel combination of featureseither explicitly or implicitly disclosed herein or any generalizationthereof and during the prosecution of the present application or of anyapplication derived therefrom, new claims may be formulated to cover anysuch features and/or combination of such features.

Although various aspects of the invention are set out in the independentclaims, other aspects of the invention comprise other combinations offeatures from the described example embodiments and/or the dependentclaims with the features of the independent claims, and not solely thecombinations explicitly set out in the claims.

It is also noted herein that while the above describes various examples,these descriptions should not be viewed in a limiting sense. Rather,there are several variations and modifications which may be made withoutdeparting from the scope of the present invention as defined in theappended claims.

1. An apparatus, comprising: at least one processor; and at least onememory storing instructions that, when executed by the at least oneprocessor, cause the apparatus at least: receive a first measurementreport from a first communication node of a mobile communication system,wherein the first measurement report includes downlink measurement datagenerated at a user device in response to a positioning reference signalsent by the first communication node; receive a second measurementreport from the first communication node, wherein the second measurementreport includes uplink measurement data generated at the firstcommunication node in response to an uplink reference signal sent by theuser device; determine an integrity of the measurement data based on acomparison of said uplink and downlink measurement data; and set anintegrity verification notification in accordance with the determinedintegrity.
 2. An apparatus as claimed in claim 1, wherein: the downlinkmeasurement data includes downlink time delay or time of arrival dataand the uplink measurement data includes uplink time delay or time ofarrival data; and determining the integrity of the measurement datadetermines whether the uplink and downlink time delay or time of arrivaldata are consistent.
 3. An apparatus as claimed in claim 2, whereindetermining whether the downlink time delay or time of arrival and theuplink time delay or time of arrival data are consistent comprisesdetermining whether a difference between the downlink time delay or timeof arrival and the uplink time delay or time of arrival is below a firstthreshold.
 4. An apparatus as claimed in claim 1, wherein: the uplinkand downlink measurement data include angle of arrival and angle ofdeparture data; and determining the integrity of the measurement datadetermines whether the angle of arrival and angle of departure data areconsistent.
 5. An apparatus as claimed in claim 1, wherein theinstructions, when executed by the at least one processor, further causethe apparatus at least to: receive a third measurement report from asecond communication node of the mobile communication system, whereinthe third measurement report includes uplink measurement data generatedat the second communication node in response to the uplink referencesignal sent by the user device, wherein the first measurement reportincludes downlink measurement data generated at the user device inresponse to a positioning reference signal sent by the secondcommunication node.
 6. An apparatus as claimed in claim 5, wherein theinstructions, when executed by the at least one processor, further causethe apparatus at least to: determine a first angle between the userdevice, the first communication node and the second communication node;determine a second angle between the user device, the secondcommunication node and the first communication node; determine a firstdistance between the first communication node and the user device; anddetermine a second distance between the second communication node andthe user device, wherein determining the integrity of the measurementdata determines whether the first and second angles and the first andsecond distances are consistent.
 7. An apparatus as claimed in claim 5,wherein the instructions, when executed by the at least one processor,further cause the apparatus at least to: determine a first angle betweenthe user device, the first communication node and the secondcommunication node; determine a second angle between the user device,the second communication node and the first communication node; anddetermine a third angle between the first communication node, the userdevice and the second communication node, wherein determining theintegrity of the measurement data determines said integrity based on asum of the first, second and third angles.
 8. An apparatus as claimed inclaim 5, wherein the first communication node is a serving base stationof the user device and the second communication node is a neighbour basestation of the user device.
 9. An apparatus as claimed in claim 1,wherein performing setting the integrity verification notificationcomprises setting an integrity verification notification signal.
 10. Anapparatus as claimed in claim 1, wherein the instructions, when executedby the at least one processor, further cause the apparatus at least to:send configuration instructions to the first communication node torequest said first and second measurement reports.
 11. An apparatus asclaimed in claim 1, wherein the instructions, when executed by the atleast one processor, further cause the apparatus at least to: estimate aposition of the user device based on angles of arrival of transmissionsfrom the user device at the first communication node and anothercommunication node and the distance between the first communication nodeand said another communication node.
 12. An apparatus, comprising: atleast one processor; and at least one memory storing instructions that,when executed by the at least one processor, cause the apparatus atleast: transmit a positioning reference signal; receive a downlinkmeasurement report from a user device, wherein the downlink measurementreport includes downlink measurement data generated at a user device inresponse to the positioning reference signal; send a first measurementreport to a server, wherein the first measurement report includes saiddownlink measurement report; receive an uplink reference signaltransmission from the user device; generate an uplink measurement reportincluding uplink measurement data generated in response to the receiveduplink reference signal; send a second measurement report to a server,wherein the second measurement report includes said uplink measurementreport; and receive an integrity verification notification signal,wherein the integrity verification notification signal is set by theuser device in accordance with an integrity determined based on acomparison of said uplink and downlink measurement report.
 13. Anapparatus as claimed in claim 12, wherein: the downlink measurement dataincludes downlink time delay or time of arrival data and the uplinkmeasurement data includes uplink time delay or time of arrival data; andwherein the integrity verification notification signal indicates whetherthe uplink and downlink time delay or time of arrival data areconsistent.
 14. An apparatus as claimed in claim 13, wherein theintegrity verification notification signal indicates whether adifference between the downlink time delay or time of arrival and theuplink time delay or time of arrival is below a first threshold.
 15. Anapparatus as claimed in claim 12, wherein the apparatus is a servingbase station of the user device.
 16. A non-transitory computer readablemedium comprising program instructions that, when executed by anapparatus, cause the apparatus to perform at least the following:receive a first measurement report from a first communication node of amobile communication system, wherein the first measurement reportincludes downlink measurement data generated at a user device inresponse to a positioning reference signal sent by the firstcommunication node; receive a second measurement report from the firstcommunication node, wherein the second measurement report includesuplink measurement data generated at the first communication node inresponse to an uplink reference signal sent by the user device;determine an integrity of the measurement data based on a comparison ofsaid uplink and downlink measurement data; and set an integrityverification notification in accordance with the determined integrity.17. A non-transitory computer readable medium as claimed in claim 16,wherein: the downlink measurement data includes downlink time delay ortime of arrival data and the uplink measurement data includes uplinktime delay or time of arrival data; and determining the integrity of themeasurement data determines whether the uplink and downlink time delayor time of arrival data are consistent.
 18. A non-transitory computerreadable medium as claimed in claim 17, wherein determining whether thedownlink time delay or time of arrival and the uplink time delay or timeof arrival data are consistent comprises determining whether adifference between the downlink time delay or time of arrival and theuplink time delay or time of arrival is below a first threshold.
 19. Anon-transitory computer readable medium as claimed in claim 16, wherein:the uplink and downlink measurement data include angle of arrival andangle of departure data; and determining the integrity of themeasurement data determines whether the angle of arrival and angle ofdeparture data are consistent.
 20. A non-transitory computer readablemedium as claimed in claim 16, wherein the instructions, when executedby the at least one processor, further cause the apparatus at least to:receive a third measurement report from a second communication node ofthe mobile communication system, wherein the third measurement reportincludes uplink measurement data generated at the second communicationnode in response to the uplink reference signal sent by the user device,wherein the first measurement report includes downlink measurement datagenerated at the user device in response to a positioning referencesignal sent by the second communication node.